1. Field of the Invention
The present invention relates to a vacuum cleaner, and more particularly, to a caster for a vacuum cleaner, which is constructed such that a travel direction of the vacuum cleaner can be changed when traveling on a surface to be cleaned and a main body of the vacuum cleaner can be maintained in a state where it is put over stairs.
2. Description of the Prior Art
Referring first to FIG. 1, the entire constitution of a conventional vacuum cleaner will be described. The vacuum cleaner comprises a main body 2 with a motor contained therein for generating suction power, a connecting hose 4 that is made of a flexible material and communicates with the interior of the main body 2, an extension tube 6 connected to the connecting hose 4 and constructed such that the length of the tube can be adjusted, and a suction nozzle 8 installed at an end of the extension tube 6 to suck air containing foreign substances from a floor surface.
The motor for producing the suction power by generating vacuum and a filtering device for filtering out the foreign substances contained in the introduced air are installed within the main body 2. A pair of wheels 2a are installed at lower portions of the main body 2 so that the main body 2 can be moved to desired locations. A caster 10 is installed at a front portion of a bottom surface of the main body 2. The caster 10 further facilitates direction change of the main body when the main body 2 travels on the floor surface. The caster 10 comprises a caster body 12 rotatably installed on the bottom surface of the main body 2, and a caster roller 14 rotatably installed in the caster body 12. Generally, since the caster body 12 should be rotatably supported on the bottom surface of the main body 2, it is formed in a circular shape when viewed from the bottom.
When cleaning is performed using the vacuum cleaner constructed as such, the suction power is generated from the interior of the main body 2 and thus the suction nozzle 8 sucks the air containing the foreign substances from a portion to be cleaned. The sucked air is introduced into the main body 2 through the extension tube 6 and the connecting hose 4. The foreign substances are filtered out by the filtering device and then collected in one side portion within the main body 2, and the filtered air is discharged to the outside after passing by the motor in the main body to dissipate heat from the motor.
However, according to the conventional vacuum cleaner constructed as such, there is inconvenience as follows.
If the cleaning is performed on stairs by using the vacuum cleaner, the vacuum cleaner can be conveniently used only when the main body 2 can be maintained in a state where it is put over the stairs. However, the bottom surface of the main body of the conventional vacuum cleaner is substantially flat, and the wheels 2a and the caster 10 are supported in a state where they protrude from a plane of the bottom surface.
In order to cause the vacuum cleaner to be maintained in the state where it is put over the stairs, there is a need for a portion to be caught by an edge of one step of the stairs in the bottom surface of the main body of the vacuum cleaner. However, since only the caster 10 protrudes in the structure of the bottom surface of the main body of the conventional vacuum cleaner, it is the caster roller 14 of the caster 10 that can be supported by the edge of the step.
However, since the conventional caster roller 14 is constructed to be rotatable and has an insufficient length in a right and left direction, there is a difficulty in supporting the main body of the vacuum cleaner in the state where it is put over the stairs. Moreover, since the caster body 12 is formed in the circular shape and simultaneously designed to be rotatable on the same plane as the bottom surface of the main body, it is rotated even though any one portion of the caster body comes into contact with a portion of the edge of the step. Therefore, it is substantially impossible to support the main body of the vacuum cleaner in the state where it is put over the linear protruding edge of the step.
As can be understood from the above, with the structure of the main body of the conventional vacuum cleaner, there is a disadvantage in that it is inconvenient to clean the stairs since the main body cannot be maintained in the state where it is put over one of the stairs.